1. Field of the invention
The invention concerns an electrical insulator device in the form of a section of pipe for a circuit distributing a relatively good conductor liquid such as a water-based coating product; it is more particularly concerned with a device of this kind in which the electrical insulation is achieved by separating two parts of said pipe section. The invention also concerns an installation for distributing relatively good conductor liquid products incorporating a device of this kind, in particular an electrostatic coating product spraying installation.
2. Description of the prior art
In an installation for electrostatically spraying a relatively good conductor coating product, such as a water-based paint as mentioned above, for example, all parts of the circuit feeding the sprayer device must in theory be insulated from ground. This is not possible if the installation is large. For example, when the paint spraying installation is part of an automobile manufacturing plant, it comprises a number of very long closed loop paint circuits which can extend right across part of the plant and which make the connections between large paint storage tanks and the various spray booths. At least one such circuit is therefore required for each coating product and another circuit of the same kind for the solvent or cleaning product. For obvious safety reasons, these circuits must be grounded. Also, in each spray booth the electrostatic sprayer devices are connected to a high-tension voltage supply. When a conductive paint is used it is therefore essential to insulate the sprayer device and the high-tension voltage supply from the parts of the structure that are necessarily grounded, in particular the product distribution circuits.
A known solution to this problem is to use an intermediate storage tank electrically insulated from ground which has a relatively small capacity and can be fed with coating product from time to time. A variable or switchable high-tension voltage source is then provided together with means for separating the intermediate storage tanks from the permanently grounded distribution circuits during coating product spraying phases.
The prior art separators for connecting or separating the pipe sections were in the open air, no precautions being taken to prevent pollution of the active parts by product lost when coupling or separating the pipe sections.
Also, as the separator must be as close as possible to the storage tank and to the sprayer to avoid wasting product on changes, it is in an area polluted by overspray and is also likely to soil the objects to be coated. What is more, despite the fact that the three components just mentioned (sprayer/storage tank/separator) are extremely close together, the system must be very compact indeed to enable it to be moved easily around the objects to be coated and so that it can very quickly be changed as a unit in the event of a fault.
An object of the invention is to achieve these three objectives, namely a compact system protected from external pollution which does not lose any product to the exterior environment.